Commission's Scientific Committee Also Confirms Whale Strandings Related to Military Sonar
FRIGATE BAY, ST. KITTS AND NEVIS (June 19, 2006) -- At its 58th Annual Meeting, the International Whaling Commission (IWC) today unanimously endorsed the recommendations of its Scientific Committee calling for measures to address the acoustic impacts on whales, fish, and other marine species from exposure to ocean noise pollution from powerful industrial air guns. These air guns, which generate explosive noise for weeks to months at a time at intensities loud enough to cross entire ocean basins, are increasingly used to find oil and gas in coastal regions throughout the world's oceans.
In its 2006 Report to the Commission, which surveys a range of threats to whales, the Scientific Committee also reported confirmation that naval sonar was in use in several recent mass whale strandings near the Canary Islands and southern Spain, where necropsies of the whales revealed tissue damage similar to that associated with "the bends" in human divers.
In a special symposium convened earlier this month, the Scientific Committee of the IWC, the world's foremost international body of whale scientists, reviewed scientific case studies of marine mammals exposed to noise from seismic air gun surveys and identified a range of potential impacts to whales. They include significant changes in feeding and other survival behaviors, damage to fish and other prey species, stranding and death. Citing this "cause for concern," the Committee adopted recommendations for mitigation, monitoring, and research to begin to address these impacts.
"There is now a broad scientific consensus about the danger high intensity air guns pose to whales and other marine species around the world," said Joel Reynolds, senior attorney and director of marine mammal protection for the Natural Resources Defense Council (NRDC), a non-governmental environmental advocacy organization based in the United States. "The IWC has defined an agenda for reform and regulation of this increasingly pervasive noise source, calling for risk-averse mitigation to protect species, increased monitoring, world-wide data collection and research, and public transparency, especially where air gun surveys may affect areas of special concern to whales and fish."
The Committee's call for action includes:
- Development and implementation of conservative mitigation procedures and protocols that represent current best practice and reflect levels of scientific uncertainty (p.51-52);
- Creation of worldwide data sets to assess the global extent of both industry and academic seismic surveys (p.50);
- Research to quantify the exposure and potential impact of noise from seismic surveys in areas of special concern, like migratory routes, feeding grounds, breeding/nursery areas, resting areas, and designated protected areas (p.50);
- Use of the most informative scientific evidence to minimize any disruption to marine species, including prey species like fish and squid (p.50);
- Collection of visual and acoustic monitoring data during seismic surveys, and the release of such data to the public (p.52);
- Research into alternate air gun signals and reduction of unnecessary air gun energy output (p.52).
"In an acoustic environment like the oceans, a relentless series of ear-splitting air gun explosions every 9 to 12 seconds for days, weeks, and even months on end can destroy the habitability of an area, no matter how essential it may be to survival of a whale population," said NRDC's Reynolds. "It's time to recognize that military sonar isn't the only source of deadly noise in our oceans. Government regulators have to insist that the oil and gas industry do more to reduce this proliferating acoustic assault."
In reaching its conclusions, the Scientific Committee highlighted a number of scientific findings, including:
- The number of seismic air gun surveys is increasing (high activity areas include the Gulf of Mexico, the Norwegian Sea, Nigeria, Brazil, Malaysia, Indonesia, India, the Northwest coast of Australia, and Sakhalin Island (Russia)), and surveys are being conducted in deeper waters in species-rich continental shelf areas, with the cumulative effect that "these activities now significantly contribute to ocean ambient noise in several ocean basins" (Ann.K.p3);
- Because seismic air gun surveys can ensonify large areas for considerable periods of time (greater than a month), the "spatial and temporal scales of seismic activities can expose large portions of a population for considerable periods of time at received levels that could collectively be considered chronic" Ann.K.p.4);
- Large whales, such as blue, fin, sei, humpback, and sperm whales, occur in relatively high numbers in areas that recently have become the focus of air gun surveys (id.);
- Small whales like critically endangered beluga whales in Cook Inlet and Hector's dolphin in New Zealand could "conflict" with seismic surveys (id.), and research is particularly needed for beaked whales, which are known to be sound sensitive (id.);
- Prey species like fish and squid respond to air gun noise, and exposure has been shown to damage hearing and significantly reduce catches of commercial fish. A narrow focus on impacts to marine mammals may have "negative ecological impacts" (id.; Ann K.p16);
- The critically endangered population of western gray whales near Sakhalin Island has been shown to alter respiration and dive patterns and overall distribution away from its feeding ground during seismic air gun surveys, and it was stressed that the critically endangered nature of this population "was reason to implement the precautionary principle by default" (Ann.K.p5-6);
- Bowhead whales in the Bering-Chukchi and Beaufort Seas are known to be very sensitive to air gun surveys and have been shown to alter their migration path by up to 35 kilometers to avoid such activities, even at relatively low levels of exposure (Ann.K.p7);
- When approached by an air gun survey vessel, endangered sperm whales in the Gulf of Mexico have been observed to stop foraging dives, reduce fluke stroke effort, and reduce echolocation buzzes, all behaviors associated with feeding (Ann.K.p7-8);
- A range of mitigation measures is recommended. Given the uncertainties of observing and understanding behavioral impacts, scheduling and timing of survey routes around seasonal distribution of species of concern is recommended. For example, following a series of humpback whale strandings along a coast subject to significant seismic air gun survey activity, the Brazilian government prohibited surveys during the whale breeding season. (Ann.K.p9)
- Because a key goal is to protect not just individual whales but entire whale populations, strategies are needed to address chronic and synergistic effects on vital parameters such as survival and reproduction. (Ann.K.p11)
The Scientific Committee also reported recent confirmation of gas and fat embolic pathologies in stranded whales examined after exposure to high intensity naval sonar near the Canary Islands and southern Spain in 2002, 2004, and 2006. These findings, reflecting symptoms like those suffered by human divers with "the bends," follow the 2004 Report of the IWC's Scientific Committee concluding that the connection between exposure to mid-frequency sonar and whale stranding and death is "very convincing and appears overwhelming."
For background on the sources and impacts of ocean noise, see NRDC's 2005 report entitled Sounding the Depths II: The Growing Threat of Sonar and Industrial Ocean Noise to Whales and Other Marine Life.